The present invention relates to a removable orthodontic appliance for aligning teeth, and more particularly, to an appliance that is individually constructed for each dental arch with teeth in their aligned positions. The appliance material possesses a combination of firmness and flexibility wherein a single appliance, with minor adjustments, will move the teeth to their final aligned positions.
Removable orthodontic appliances have been used in orthodontics since the early part of the 20th century. To clarify the description of the invention certain dental terms should be understood. Upper and lower teeth are termed maxillary and mandibular teeth, respectively. Front teeth are anterior teeth and back teeth are posterior teeth. Anterior teeth are incisors and are named centrals, laterals, and cuspids in order from the midline to the posterior. The posterior teeth, from anterior to posterior, are first, second, and third molars. Individual teeth are described according to their surfaces. The distal surface is towards the back of the mouth and the mesial is the surface towards the front of the mouth. The lingual or palatal surface is on the tongue side of the teeth. The labial or buccal surface is on the cheek or lip side of the teeth. The occlusal surface is where the maxillary and mandibular teeth meet.
Prior appliances required, many times, complicated adjustments and were not predictably effective in aligning crooked teeth. Another group of appliances were developed wherein the appliance is fabricated over a model of repositioned teeth. In this group is a tooth positioner, as disclosed in U.S. Pat. No. 2,531,222. The tooth positioner is one piece, moving the upper and lower teeth simultaneously. This appliance is very demanding on patients as they are bulky, uncomfortable, and prevent patients from speaking. Also in this group, are appliances known as spring-alignment appliances. These appliances are designed to correct minor incisor rotations. The appliance is constructed over a model of repositioned teeth. Labial and lingual wires are formed and labial and lingual plates are formed over the wires. The acrylic plates apply the pressure to the teeth. These appliances cannot be adjusted and are not particularly effective for tooth movement. Another in this group, is the INVISILIGN appliance, which is made by vacuum forming a clear maternal over many models of progressively positioned teeth. The INVISILIGN appliance uses a relatively hard material which prevents an individual appliance from producing substantial tooth movement. For this reason, a series of appliances have been constructed where the movement is progressive, each succeeding appliance applies slightly more movement than the prior appliance INVISILIGN claims average treatment is 9-15 months and each pair of all liners is worn two weeks. The number of appliances used would be from 36 to 60. The INVISILIGN appliances are very costly and their construction is difficult and very proprietary as the progressive tooth movement is computer generated by only the INVISILIGN company. The orthodontic profession to the present has an unfilled need for an effective, aesthetic, easy to construct, and cost-efficient removable appliance for aligning teeth.
An object of the present invention is to provide an esthetic, easy to wear, effective, removable orthodontic appliance. The removable appliance has its greatest usefulness when the posterior teeth are well positioned and the anterior teeth are misaligned, maloccluded, or otherwise in need of repositioning. The posterior teeth are the anchor for the appliance.
A preferred embodiment of the present invention comprises a sheet of 0.030 in. clear polypropylene thermo- vacuum formed to a model of the patient""s teeth where the misaligned six anterior teeth are repositioned into an aligned position. The tooth movement being most effective where all six anterior teeth are repositioned. The concept of moving at least six anterior teeth is one of the keys of the success of this appliance. The embodiment is characterized by material that has a flexibility which allows a single retainer to move the misaligned teeth and into their final positions. Other materials, ranging from 0.020 inch thickness to 0.080 inch thickness may be used if they possess comparable flexibility to move the teeth. The appliances are made separately for each jaw, allowing the patient to wear appliances near full-time, if necessary. The appliance may also be constructed to move posterior teeth. An additional object of this invention is to ease the construction of the appliance. A single tooth repositioned model is usually all that is required, making construction of the appliance easy and economic. The single appliance ability of this appliance to align the teeth is further enhanced by stretching and cutting adjustments to allow the appliance to be seated in the mouth and retightening adjustments enabling the single appliance to move the teeth to a final aligned position.
In another embodiment of the present invention, the appliance is constructed with an embedded wire 0.020 inch to 0.060 inch in diameter to widen or narrow the posterior arch width. This is particularly effective for correction of posterior cross bites. The embedded wire has a further advantage of increasing stability and retention of the appliance. In a further embodiment of the appliance, a lingual shield is formed to prevent the adverse effect of the tongue upon the teeth, or as is commonly called, tongue thrusting, The shield is usually placed lingual to the anterior teeth, but may be used lingual to the posterior teeth for lateral tongue-thrusting patients. The shield is comfortable to wear and easy to construct. The template shield is affixed to the model in the lingual vertical position and the appliance is formed over the model, including the shield template. Other objects, features, and advantages of the invention will be apparent from the accompanying sheets of drawings wherein like reference numerals refer to like parts.